Arrhythmia recording and control system and method of operation

ABSTRACT

An electrocardiographic signal is continuously displayed in a series of consecutive horizontal traces on the face of a cathoderay tube with each trace being vertically offset from the preceding trace in response to a sequentially stepped reference signal applied with the electrocardiographic signal to the cathode-ray tube vertical deflection amplifier. The cathode-ray tube display is photographed onto one quadrant of a 35 millimeter microfilm.

United States Patent m13,585,988

[72] Inventors Walter F. Cl'tigh 2,457,744 12/1948 Sturm 128/206 Newport; 3,267,933 8/1961 Mills et a1. 128/206 Army i J 'q m i b th f. M lllh; 3,281,861 /1966 Simopoulos et a1 346/1 10 Ml J- sdll'llitl, North 3,348,229 10/1967 Freas 346/1 10 X [2 11 Appl. N0- 777353 3,434,151 3/1969 Bader et a1 128/206 X S d f?"- gg: FOREIGN PATENTS atente une [73] Asian MM Mining & Mmdmuring 639,233 6/1950 Great Britain 128/206 Company Primary Examiner--Wi1liam E. Komm St. Paul, Minn. Attorney-Kinney, Alexander, Sell, Steldt & Delahunt [$4] ARIHY'IHMIA RECORDINGAND CONTROL SYSTEM AND METHOD OF OPERATION 14 Claims, 6 Drawing Figs.

ABSTRACT: An electrocardiographic signal is continuously displayed in a series of consecutive horizontal traces on the face of a cathode-ray tube with each trace being vertically offset from the preceding trace in response to a sequentially stepped reference signal applied with the electrocardiographic signal to the cathode-ray tube vertical deflection amplifier. The cathode-ray tube display is photographed onto one 7 2,098,695 1 1/1937 Southwick 12812.06 X quadrant of a 35 millimeter microfilm.

I 7Q 667 5 VFKT/CAL A, 5/ /1442 /6 DifLfU/d/Y 7 s G) flMPL/F/ff flMPl/F/ER 761 o 0 74 (AW/00594) x VFW/ML 36 ox/uoxo f fifFlECT/WY 3Z\ 0/6/7/14 r0 AWL/Hm Z4 fllV/IL 06 G) ,a/mm/mmra HUM-Mm RECORD ran rm LOG/C pmfmm, 1 (An/00mm (/RCU/T -46 AMPLIFIER 05mm? N 42 Z0 58 34- ZZ- UNBMNK/l/G f6 60 .S'WEEP )4 meal/r 62 OWHODEKHY 44 OSUZMJMPE ARRHYTHMIA RECORDING AND CONTROL SYSTEM AND METHOD OF OPERATION I BACKGROUND OF THE INVENTION The present invention relates to displaying and recording physiological data in analog representations of biomedical phenomena. The invention particularly relates to monitoring and recording arrhythmia in electrocardiographic waveforms. A waveform of sufficient duration for detection and classification of arrhythmia is monitored on a cathode-ray tube and recorded in one quadrant of 35 millimeter microfilm.

In the prior art, arrhythmia detection and classification have been made from examination of pen and chart paper recordings of electrocardiographic waveforms. The pen is deflected on the chart paper in response to a galvanometer movement which responds to the electrocardiographic signal. There are several disadvantages attendant to the pen and chart paper technique. The inertia of the system impairs recording in response to the higher frequency components of the electrocardiographic signal wherein arrhythmia may occur. Recording on chart paper provides a waveform of such length that it is not convenient to compare the various waveform cycles. Thus, the chart is usually cut into sections which are mounted on a-single page to facilitate analysis. The size of the chart paper recordings also presents additional storage requirements.

The prior art also provides for monitoring electrocardiographic waveforms on a cathode-ray tube and for recording electrocardiographic wavefonns from a cathode-ray tube. A system for such monitoring and recording is described in the pending U.S. Pat. application Ser. No. 676,860, filed Oct. 20, 1967, now US Pat. No. 3,434,151, by two of the present inventors, Messrs. Landy and Schmitz, and by William F. Bader. However, the prior art system of electrocardiographic monitoring and recording with a cathode-ray tube does not provide electrocardiographic waveforms of a duration sufficiently long for detection and classification of arrhythmia. While there is a difference of opinion concerning a desirable waveform duration for detection and classification of arrhythmia, some cardiologists believe that somewhere between and 60 seconds of approximately continuous electrocardiographic waveform is required. Present cathode-ray tube systems provide a trace having resolution sufficiently high for cardiological analysis for only approximately 6 to 12 seconds, depending on tube size. An arrhythmia could be detected from a trace as short as 6 to 12 seconds if recurrence of the arrhythmia in the particular patient was sufficiently high to occur in such a short time span. Nevertheless, even if arrhythmia did occur in the 6 to 12 second interval, some cardiologists are of the opinion that too few heart beats occur in this relatively short interval for optimum classification and interpretation of the nature of the arrhythmia.

SUMMARY OF THE INVENTION The present invention provides for displaying on a cathoderay tube for monitoring and recording an approximately continuous trace of an electrocardiographic waveform over a consecutivetime for a duration sufficient for arrhythmia detection and classification.

An electrocardiographic signal is summed with a direct current reference signal to deflect vertically the electron beam in a cathode-ray oscilloscope. The level of the reference signal is periodically varied at a rate synchronized with the rate of the signal applied to deflect horizontally the electron beam of the oscilloscope so that each scan line on the oscilloscope is at a different direct current level. The level of the reference signal is changed in a decreasing stepped sequence so that the electrocardiographic waveform is displayed on the face of the cathode-ray oscilloscope in a series of horizontal traces. The amplitude of the vertical deflection on the scope is chosen to provide sufficient resolution for cardiological analysis of the waveforms and to be ofa low enough amplitude to allow a plurality of horizontal traces on the face of the given oscilloscope.

To provide a trace of a longer duration than can be displayed on the face of one cathode-ray oscilloscope, additional cathode-ray oscilloscopes are provided for consecutively displaying the waveform following the last trace line on the proceeding scope.

' The cathode-ray oscilloscope is blanked during each interval while the level of the reference signal is being changed so that the retrace pattern will not be displayed on the scope.

The image on the cathode-ray oscilloscope is photographed onto microfilm. In a preferred embodiment, the traces on two cathode-raytubes are photographed on one quadrant of 35 millimeter microfilm.

The present invention may be practiced in combination with the prior art system for providing a multiplexed display of electrocardiographic signals described in the aforementioned pending application SER. No. 676,860 now U.S. Pat. No. 3,434,151. In accordance with this prior art system, the sequence in which the signals are to be displayed is programmed. First, the electrocardiographic signals are displayed on cathode-ray tubes, monitored and photographed on microfilm. A single electrocardiographic signal is chosen for display as a rhythm lead. The rhythm waveform is then displayed on one of the cathode-ray tubes and photographed. At this point, the present invention comes into operation. The signal chosen for rhythm display is displayed for arrhythmia analysis by combining it with the aforementioned periodically varied reference signal to provide a display on additional cathode-ray tubes which are then photographed on a separate quadrant of the same 35 millimeter microfilm on which the electrocardiographic and rhythm waveforms are displayed.

BRIEF DESCRIPTION OF THE DRAWING .showing the internal connections of the digital-to-analog converter and switching control logic circuit shown in block form in FIG. 2;

FIG. 4 shows the waveforms at the inputs and outputs of the digital-to-analog converter and switching control logic circuit of FIG. 3;

FIG. 5 is a representation of the display on microfilm of the plurality of electrocardiographic waveforms; and

FIG. 6 is a representation of a display on microfilm of an electrocardiographic signal displayed for arrhythmia analysis.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, an electrocardiographic input signal is provided on line 10 and amplified in signal amplifier 12 to provide an amplified electrocardiographic signal on line 14. A direct current reference signal is provided on line 16 from digital-toanalog converter and switching control logic circuit 18. The direct current level of the reference signal provided on line 16 is periodically varied in a stepped sequence in response to a periodic signal on line 20 from sweep generator 22. The digital-to-analog converter and switching control logic circuit 18 commences to provide the stepped sequence reference signal on line 16 in response to a start signal on line 24. The amplified electrocardiographic signal on line 14 and the reference signal on line 16 are added together in summing amplifier 26 to produce a summed signal on line 28 which is applied to vertical deflection amplifier 30 to vertically deflect the electron beam in record cathode-ray oscilloscopes 32 and 34. The vertical deflection amplifier 30 provides an output signal on line 36 which is applied to record cathode-ray oscilloscope 32 on line 38 and to record cathode-ray oscilloscope 34 on line 40.

Record cathode-ray oscilloscopes 32 and 34 are provided with horizontal deflection signals on lines 42 and 44 respectively by sweep generator 22 via line 46 through horizontal deflection amplifier 48 and line 50. The horizontal deflection signals from sweep generator 22 are synchronized with the sequentially stepped signal from digital-to-analog converter and switching control logic circuit 18 to provide a complete sweep for each direct current reference signal level.

To provide a trace on only one oscilloscope at a time and to blank the oscilloscope during the retrace interval between sweeps, unblanking amplifier circuit 52 is provided. Unblanking amplifier circuit 52 receives a periodic control signal on line 54 from sweep generator 22 in response to which the cathode-ray oscilloscopes are blanked during the retrace intervals. The unblanking signal produced by unblanking amplifier circuit 52 is of sufficient magnitude to, when applied to the grid of a cathode-ray tube, accelerate the electron beam to impinge upon the tubes electron sensitive face. The output signal of unblanking amplifier circuit 52 is fed on line 56 to relay 58. Relay 58 provides the unblanking signal on either line 60 to the grid of record cathode-ray oscilloscope 32 or on line 62 to the grid of record cathode-ray oscilloscope 34. The relay 58 switches the amplified unblanking signal between lines 60 and 62 in response to a control signal on line 64 from digital-to-analog converter and switching control logic circuit 18.

A monitor cathode-ray oscilloscope 66 is provided for viewing the electrocardiographic signal during such time as it is being displayed on cathode-ray oscilloscopes 32 and 34. The electrocardiographic signal from line 14 is applied on line 68 to vertical deflection amplifier 70, thence to the vertical deflection control on monitor cathode-ray oscilloscope 66 on line 72. Monitor cathode-ray oscilloscope 66 also receives a horizontal deflection signal from horizontal deflection amplifier 48 on line 74 and is also unblanked in synchronism with the record cathode-ray oscilloscopes vby a signal on line 76 from unblanking amplifier circuit 52.

ln operation, the electrocardiographic input signal is applied on line and a start signal is applied on line 24. The amplified electrocardiographic signal on line 14 is summed with the time varying stepped reference signal on line 16 to provide a spaced plurality of horizontal traces on record cathode-ray oscilloscope 32. The control signal on line 64 from the analog-to-digital converter to relay 58 directs relay 58 to blank record cathode-ray oscilloscope 34 continuously until such time as a given plurality of traces have been displayed on cathode-ray oscilloscope 32. Upon completion of this given plurality of traces on record cathode-ray oscilloscope 32, the digital-to-analog converter and switching control logic circuit resets the direct current level of the reference signal to repeat the series of stepped reference signals on line 16 and changes the signal on line 64 to relay 58 so as to thereafter unblank record cathode-ray oscilloscope 34 and to continuously blank record cathode-ray oscilloscope 32. The consecutive series of electrocardiographic signals are thus continued from record cathode-ray oscilloscope 32 to record cathode-ray oscilloscope 34.

In the embodiment illustrated in FIG. 2, an electrocardiographic signal is displayed for arrhythmia analysis in an electrocardiographic recording system of the type described in the aforementioned U.S. Pat. application Ser. No. 676,860, now U.S. Pat. No. 3,434,151, wherein a plurality of amplified electrocardiographic signals are multiplexedly displayed on cathode-ray tubes. Amplified electrocardiographic signals are received on 3-channel lines 78 and 80 by 4-channel signal multiplexers 82 and 84 respectively. At the origin of the amplified electrocardiographic signals, six signals are simultaneously transmitted, one to each of the channels represented by lines 78 and 80 to record all 12 standard electrocardiographic scalar signals, I, ll, [11, aVR, aVL, aVF, V,, V,, V V V and V The l2 signals are transmitted in two sets of six simultaneous signals. These sets are alternatively transmitted over the six channels representedby lines 78 and 80. The 4-channel level multiplexers 86 and 88 receive a plurality of direct current level reference signals on 3-channel line 90 and 4-channel line 92. The output of signal multiplexer 82 on line 94 is applied to one input channel of signal multiplexer 84 by line 96 and to relay 98 by line 100. Relay 98 also receives on line 102 a signal from the output provided by signal multiplexer 84 on line 104. Relay 98 has a single output line 106 to the input of summing amplifier 108. The output signal of multiplexer 84 on line 104 is also applied to summing amplifier 110 on line 112. The reference signal from level multiplexer 86 is applied on line 114 to summing amplifier 108 and the reference signal from level multiplexer 88 is applied on line 116 to summing amplifier 110.

A lead sequencer control 118 operating in response to a signal on line 120 from a multiphase clock 122 provides on 4- channel line 124 clocking signals on 4-channel lines 126 and 128 to signal multiplexers 82 and 84 and on 4-channel lines 130 and 132 to level multiplexers 86 and 88 to synchronize the operation of these four multiplexers. Rhythm lead selector 134 provides on line 136 to lead sequencer control 118 a designation of a single electrocardiographic signal to be displayed as a rhythm signal, In accordance with the prior art electrocardiographic recording system for displaying simultaneous multiplex signals described in pending application Ser. No. 676,860, now US. Pat. No. 3,434,151, the rhythm signal would be provided for only one trace line.

In accordance .with the present invention, the rhythm lead is provided for a plurality of traces lines. This additional capability is made possible by the digital-to-analog converter and switching control logic circuit 138. The digital-to-analog converter and switching control logic circuit 138 provides a varying level sequentially stepped direct current signal to one channel of level multiplexer 86 on line 140. The level of the signal on line 140 is stepped in response to the periodic signal received on line 142 from sweep generator 144. Sequential stepping of the direct current signal on line 140 commences in response to simultaneous signals from the lead sequencer control 118 on line 146 from line 147 and from the arrhythmia record control 148 on line 150 to provide an enabling signal on line 151 at the output of wired AND gate 153. The signal on line 147 is provided by lead sequencer control 118 only after the electrocardiographic signals and the single line rhythm signal have been provided by the summing amplifiers 108 and 110. At the beginning of the rhythm trace, the lead sequence control 118 indicates to level multiplexer 86 that it should thereafter produce output signals responsive only to signals on line 140.

Also upon commencing sequential stepping of the signal on line 140, the digital-to-analog converter and switching control logic circuit 138 produces a control signal on line 152 which is applied to relay 98 by line 154 and to relay 156 on line 158. Control signals on line 154 indicate to relay 98 whether the signal input to summing amplifier 108 is to be taken from signal multiplexer 82 or signal multiplexer 84. During commencement of sequential stepping relay 98 in response to the control signal on line 154 applies the output from signal multiplexer 84 to summing amplifier 108. The signal multiplexers 82 and 84 provides a signal from only a single input channel. The particular input channel on signal multiplexer 82 or 84 on which the arrhythmia signal is to be taken is indicated by a signal on line 124 from lead sequencer control 118 to signal multiplexers 82 and 84 on 4-channel lines 126 and 128. Signals normally led into signal multiplexer 82 are led into signal multiplexer 84 on line 96.

The multiplexed plurality of electrocardiographic signals are normally displayed on record cathode-ray tubes 160 and 162 from whence they can be photographed onto microfilm by camera processor unit 164. The camera processor unit 164 is a Model 3M 2000 Filmsort" processor camera sold by the Minnesota Mining and Manufacturing Company of Saint Paul, Minnesota. This processor camera unit is capable of recording the standard twelve electrocardiographic waveforms and a rhythm waveform on one quadrant of 35 millimeter microfilm. Monitor cathode-ray tubes 166 and 168 are provided for viewing the waveforms during the recording process. The signal displayed for arrhythmia analysis is provided on arrhythmia cathode-ray tubes 170 and 172 from whence photographs may also be taken by camera processor unit 164.

The horizontal deflections of all cathode-ray tube electron beams are synchronously scanned by asignal produced by sweep generator 144 and led on line 174 through horizontal deflection amplifier 176 and on line 178 to the respective horizontal deflection inputs 180-190 of the cathode-ray tubes.

Monitor cathode-ray tube 166 and record cathode-ray tube 160 receive on lines 192 and 194 respectively, an amplifier vertical deflection signal from summing amplifier 108 through line 196, vertical deflection amplifier 198, line 200, relay 156 and line 202. Monitor cathode-ray tube 168 and record cathode-ray tube 162 simultaneously receive amplified vertical deflection signals on lines 204 and 206 respectively from summing amplifier 110 by way of line 208, vertical deflection amplifier 210 and line 212. The vertical deflection signals to the arrhythmia cathode-ray tubes 170 and 172 are simultaneously provided on lines 214 and 216 from summing amplifier 108 by line 196, vertical deflection amplifier 198, line 200, relay 156 and line 218. Relay 156 switches the vertical deflection output signal from summing amplifier 108 from line 202 to line 218 in response to the control signal initiated on line' 158 by the digital-to-analog converter and switching control logic circuit 138 upon commencement of the stepping sequence.

To control unblanking of the cathode-ray tubes, a periodic signal is provided on line 220 from sweep generator 144 to unblanking amplifiers 222-228 on lines 230236 respectively.

'The signal on line 220 is a composite signal. All unblanking amplifiers are provided with signals from sweep generator 144 to blank the cathode-ray tubes to which they are connected during the interval between horizontal traces. The periodic signals on lines 142, 174 and 220 from sweep generator 144 are synchronized to provide one electron beam scan in the cathode-ray tube during each sequentially stepped reference signal level provided by the digital-to-analog converter and switching control logic circuit 138 and to blank the cathoderay tubes during the interval in which the level of the reference signal is stepped.

In addition to the end of trace blanking signals, the composite signal on line 220 is also made up of a signal to blank the cathodeqay tubes during the intervals between each multiplexed signal segment when the system is in its multiplexing mode of operation. This second signal on line 220 is produced by sweep generator 144 in response to a periodic signal on line 221 from multiphase clock 122 and to a control signal on line 223 from lead sequencer control 118. In response to the signal received on line 223 indicating that the plurality of electrocardiographic input signals are being multiplexed, the sweep generator 144 receives the signals on line 221 from multiphase clock 122 to produce on line 220 that signal which initiates blanking by the unblanking amplifiers 222-228 between each multiplexed signal segment display so as not to display on the face of the cathode-ray ray tubes the trace lines between ryw in t d iss s t When notin the multiplexing mode, thedisplay of a single 'unnaria 'msifier' 222 rovides at; unblanking igs a1 ":6"

monitor cathode-ray tube 166 on line 238. Unblanking amplifier 224 provides an unblanking signal to the grid of monitor cathode-ray tube 168 on line 240. Unblanking amplifier 228 provides an unblanking signal to the grid of record cathoderay tube 160 on line 242. Unblanking amplifier 226 provides an unblanking signal on line 243 through relay 244. Relay 244 responds to the control signal on line 158 to provide on line 245 an unblanking signal to the grid of record cathode-ray tube 162 to blank cathode-ray tube 162 upon the beginning of the sequential stepping of the signal on line and simultaneous therewith through relay 246 via line 247 to either of lines 248 or 250 to the grids of arrhythmia cathode-ray tubes 170 and 172 respectively. Relay 246 is controlled by a signal on line 251 from digital-to-analog converter and switching control logic circuit 138. lnitially the unblanking signal is provided on line 248 to cathode-ray tube 170 thereby blanking arrhythmia cathode-ray tube 172. Upon completion of a predetermined number of traces on arrhythmia cathode-ray tube 170, the digital-to-analog converter and switching control logic circuit 138 having counted the number of sequential steps produced on line 140 resets the level of the signal on line 140 to that at the beginning of the first sequence. Simultaneous with resetting the level on line 140, the digital-to-analog converter and switching control logic circuit 138 provides a signal on line 251 to cause relay 246 to switch the unblanking signal to arrhythmia cathode-ray tube 172 andv to blank arrhythmia cathode-ray tube 170 thereby providing for a consecutive trace on the two arrhythmia cathode-ray tubes 170 and 172 responsive to the electrocardiographic signal selected for analysis.

Camera processor unit 164 receives a signal on line 252 from lead sequencer control 118 to commence exposure of the film upon commencement of the recording sequences.

The horizontal deflection rate of the signals from sweep generator 144 may be controlled by a signal provided on line 254 from sweep rate selector control 256. The gain of summing amplifiers 108 and 110 may be controlled by signals applied on lines 258 and 260 respectively by line 262 from gain selector control 264.

A lamp driver 266 is provided to drive indicating lamps positioned adjacent to the faces of the arrhythmia cathode-ray tubes to indicate the gain and horizontal deflection rate at which the signals are being displayed and the source of the signal. Lamp driver 266 receives a signal on line 265 from gain selector control 264 to indicate signal gain, receives a signal on line 267 from sweep rate selector control 256 to indicate signal horizontal deflection rate and a signal on line 269 from lead sequencer control 118 to indicate which electrocardiographic input signal has been selected for arrhythmia display.

The lamp driver 266 is turned on in response to a signal on line 268 from digital-to-analog converter and switching control logic circuit 138.

A signal is provided on line 270 from digital-to-analog converter and switching control logic circuit 138 to lead sequencer control 118 in response to a signal received on line -l51 indicating the commencement of an arrhythmia record cycle so as to prevent the lead sequencer control 118 from initiating a card processing signal to camera processor unit 164 on line 252 prior to the end of the recording of the electrocardiographic signal from arrhythmia cathode-ray tubes 170 and 172. Ordinarily, the camera processor unit processes the photographs upon completion of the display of the electrocardiographic and rhythm signals on record cathode-ray tubes and 162.

The digital-to-analog converter and switching control logic circuit 138 may be cleared and reset to its original starting position in response to a control signal on line 272 from lead sequencer 118.

F IG. 3 is a schematic circuit diagram of the digital-to-analog converter and switching control logic circuit used in the preferred embodiment of the present invention. Each circuit element is identified by reference numeral and the identification and value of each element is given in the following table:

Flip-Flops N PN Transistor Z74 DTL 948 308 2N3566 276 DTL 948 Operational Amplifier mmas! I Flip-Flops N PN Transistor 278 DTL 948 309 Motorola Model v\K I433 280 DTL 948 Diodes 282 DTL948 3l0 FD I NANDGates 3l2FDl00 284 DTL 930 Variable Resistors 286 DTL 930 314 K!) set at 4 K!) 288 DTL 946 3 l6 10 K!) set at 2 K!) 290DTL930 SISlOKQsetatIKQ 292 DTL 930 320 l0 K!) to vary offset NOR Gates 1 321 10 K!) to vary gain 294 DTL 946 Resistors 296 DTL 946 322 1 KG 298 DTL 946 324 I0 K!) 300 DTL 946 326 l5 l2 Inverters Capacitors 302 DTL 946 328 .025 pf 304 DTL 946 330 .025 pf 306 DTL 946 332 22 cf The waveforms at each of the inputs and outputs of the digital-to-analog converter and switching control logic circuit 138 are shown in FIG. 4.

FIG. 5 is a representation of microfilm image of the multiplexed electrocardiographic signals and rhythm signal. Each waveform is identified as to its source by lead designations l, ll, Ill, aVR, aVL, aVF, V,, V,, V,, V V and V and the rhythm lead by Rh. Those waveforms representing signals horizontally deflected at a rate of 50 millimeters per second are identified by the numeral 50. Those waveforms represent ing signals having a gain of 2 millivolts per centimeter are identified by the numeral 2 and those having a gain factor of one-half millivolts per centimeter are identified by the numeral one-half. If no identification as to the gain or sweep is given, the signals are horizontally deflected at 25 millimeters per second and have a gain factor of l millivolt per centimeter.

FIG. 6 is a representation of a microfilm image of the electrocardiographic signal recordedfor arrhythmia analysis in ac cordance with the present invention. 6 sweeps are produced on the cathode-ray tube 170 and 5 sweeps are produced on cathode-ray tube 172. A time interval between each sweep is approximately 35 milliseconds. The source of the waveform is identified as electrocardiographic signal ll at a sweep rate of 50 millimeters per second and amplified by a gain factor of 2.

To summarize operation, the standard 12 scalar leads and standard 12 electrocardiographic signals received on lines 78 and 80 are first monitored on monitor cathode-ray tubes 166 and 168 and simultaneously recorded on record cathode-ray tubes 160 and 162 from which they may be photographed by camera procemor unit 164. Next the rhythm lead is monitored on monitor cathode-ray tube 168 and simultaneously recorded on and photographed from record cathode-ray tube 162. The arrhythmia record control 148 is actuated to provide a signal on line 150 to the digital-to-analog converter and switching control logic circuit 138. At the end of the rhythm recording, the first line of arrhythmia recording on cathoderay tube 170 commences. At the end of each line of the arrhythmia recording, a Zcentimeter vertical offset is applied by digital-to-analog converter and switching control logic circuit 138 to the vertical deflection amplifier 198 which in turn offsets the trace being scanned on the arrhythmia cathode-ray tube 170 by 2 centimeters from the preceding trace. At the end of the sixth line, arrhythmia cathode-ray tube 170 is blanked and arrhythmia cathode-ray tube 172 is unblanked. The vertical offset applied to the vertical amplifier 198 is returned to the same level as for line one and the seventh line is recorded on arrhythmiacathode-ray tube 172. At the end of each :line again a 2-centimeter offset is applied to cathode-ray tube 172. At the end of the eleventh line, the microfilm is processed. The rhythm monitor cathode-ray tube is used to continuously monitor the arrhythmia recording.

The system of the present invention isalso applicable to rapid displaying and recording of other biological phenomena having high frequency components; and requiring a long duration trace for analysis.

While the present invention has been described herein as providing a cathode-ray tube face as the electron sensitive medium upon which the electron beam responsive to the electrocardiographic signal is impinged, the system of the present invention is also usable with an electron beam recorder. The electrocardiographic signals could, in accordance with the present invention, be directly recorded on any electron sensitive medium such as photographic film as well as being recorded on film by means of photographing an image displayed on the phosphorescent face of the cathode-ray tube.

It is readily seen that the present invention provides advantages in arrhythmia monitoring and recording. in a preferred embodiment, a waveform of sufficient duration for cardiological analysis may be reproduced on one quadrant of 35 millimeter microfilm using a sweep rate of 25 millimeters per second and a gain of 1 millivolt per centimeter and by varying the level of the sequential steps of the digital-to-analog converter and switching control logic circuit by an amount sufficient to offset each succeeding trace by 2 centimeters. A continuous trace of 11 lines of electrocardiographic signals, each 14 centimeters in length, are produced on two cathoderay tubes to provide an electrocardiographic waveform having a duration of 61.95 seconds. The blanked retrace time between each waveform is controlled to be not more than 35 milliseconds. The first six lines are recorded on one cathoderay tube and the last five lines are recorded on a second adjacent cathode-ray tube. With the system of the present invention, electrocardiographic waveforms may be produced on microfilm and printed on 8% inch by l 1 inch (approximately 22 cm. X28 cm.) paper for arrhythmia analysis within a matter of seconds. The high frequency components of the electrocardiographic signals are reproduced so that they may be analyzed and their significance determined. The waveforms are produced rapidly and on microfilm which is convenient for storage. The microfilm image also indicates the lead, the sweep rate and the amplification factor of the recorded waveform. When used with the multiplexed electrocardiographic system, the various electrocardiographic signals maybe monitored periodically and any given electrocardiographic signal canbe chosen for a recording of sufficiently long duration for arrhythmia analysis whenever deemed appropriate.

We claim:

1. A system for providing for physiological analysis a waveform display representative of a biomedical phenomenon, comprising;

means for generating an electron beam;

means operatively coupled to the electron beam generating means for providing an electron sensitive medium of a predetermined width in position capable of receiving impingement of said generated electron beam for providing a waveform display in response to said impingement;

means for providing a periodic signal;

means connected to the periodic signal providing means and operatively coupled to the electron beam generating means for periodically horizontally scanning said electron beam across said width of said electron sensitive medium, in response to said periodic signal; means for providing an electrical signal having a voltage? amplitude representative of said biomedical phenomenon; means connected to the electrical signal providing means for amplifying the voltage of said provided electrical;

means operatively coupled to the amplifying means and connected to the direct current reference signal providing means for summing said voltages of said amplified electrical signal with said direct current reference signal to provide a summed signal representative thereof; and

means connected to the summing means and operatively coupled to the electron beam generating means for vertically deflecting said electron beam in response to said summed signal for providing a sequential plurality of consecutive electron beam scans upon said provided electron sensitive medium representative of said amplified electrical signal to consecutively provide a waveform display representative of said biomedical phenomenon during each period stepped sequence of reference signal voltage levels.

2. The system of claim 1, in which the signal representative of the biomedical phenomenon is an electrocardiographic signal, which system further comprises means 'aiieaiita' eoabed toth eelectron beam generating means for variably amplifying said deflection of said electron beam in response to said summed signal to provide a said waveform of sufficient resolution for arrhythmia analysis of said waveform.

3. The system of claim 2, further comprising means operatively coupled to the means for providing said periodic signal for varying said periodic signal to provide a said waveform of sufficient resolution for arrhythmia analysis of said waveform.

4. The system of claim 1, further comprising means operatively coupled to the electron beam generating means and to the means for providing said periodic signal for blanking the impingement of said electron beam during the interval in which the level of said reference signal varies.

5. The system of claim 1, further comprising a second means for generating a second electron beam;

a second means operatively coupled to the electron beam generating means for providing a second electron sensitive medium of a predetermined width in position capable of receiving impingement of said generated second electron beam for providing a waveform display in response to said impingement;

both of which recited second means are operatively coupled to the various means of the system in the same manner as the first recited electron beam generating means and first electron beam medium providing means are so operatively coupled; and

switching means operatively coupled to the means for providing said direct current reference signal and operatively coupled to both electron beam generating means for alternatively providing waveform displays on each provided electron sensitive medium during alternative periodic sequences of the reference signal.

6. The system of claim 1, in which the synchronizingvmeans are connected to the periodic signal providing means for periodically varying the direct current reference signal in a stepped sequence in response to said periodic signal.

7. A system for providing for physiological analysis a waveform display representative of biomedical phenomena,

comprising means for generating an electron beam;

means operatively coupled to the electron beam generating means for providing an electron sensitive medium of a predetermined width in position capable of receiving impingement of said generated electron beam for providing a waveform display in response to said impingement;

means for providing a periodic signal;

means connected to the periodic signal providing means and;operatively coupled to the electron beam generating means for periodically horizontally scanning said electron beam across said width of said electron sensitive medium in response to said periodic signal;

means for providing a plurality of electrical signals having 7 voltage amplitudes representative of a plurality of biomedical phenomena;

means connected to the electrical signal providing means for amplifying the voltages of said provided electrical signals;

means for providing a plurality of bias signal having different discrete direct current voltage levels;

means connected to the amplifying means for multiplexing said plurality of amplified electrical signals in a predetermined periodic sequence to provide a first multiplexed signal representative thereof;

means connected to the bias signal providing means for multiplexing said plurality of bias signals in said predetermined periodic sequence to provide a second multiplexed signal representative thereof;

means operatively coupled to both multiplexing means for summing said voltages of said first and second multiplexed signals to provide a summed signal representative thereof;

means connected to the summing means and operatively coupled to the electron beam generating means for vertically deflecting said electron beam in response to said summed signal for providing a multiplexed electron beam scan upon said provided electron sensitive medium representative of said plurality of amplified electrical signals to simultaneously provide a plurality of waveform displays representative of said biomedical phenomena; and

means operatively coupled to the summing means, to the bias signal providing means and to the amplifying means for selectively providing to the summing means a single said bias signal and one of said plurality of said amplified provided electrical signals corresponding to a single said biomedical phenomenon for enabling the summing means to provide a summed signal representative of the voltages thereof to the means for vertically deflecting said electron beam to provide as a rhythm waveform a consecutive electron beam scan upon said provided electron sensitive medium representative of said selectively provided amplified electrical signal to provide a waveform representative of said corresponding biomedical phenomenon, which system is characterized by the improvement further comprising means for providing a direct current reference signal, the voltage level of which periodically varies in a decreasing stepped sequence, which means for providing said direct current reference signal comprises 4 means for synchronizing said direct current reference signal in accordance with said periodic signal to provide a consecutive scan of said electron beam across said width of said electron sensitive medium once during the duration of each said reference signal voltage level; and

means operatively coupled tothe summing means, to the amplifying means and to the direct current reference signal providing means for enabling the summing means to sum the voltage of said selectively provided amplified electrical signal with the voltage of said direct current reference signal to provide a summed signal representative thereof to the means for vertically deflecting said electron beam to provide a sequential plurality of consecutive electron beam scans upon said provided electron sensitive medium representative of said selectively provided amplified signal to consecutively provide a waveform display representative of said corresponding biomedical phenomenon during each periodic stepped sequence of reference signal voltage levels.

" '8. Anathema providing rat saysiaiagizafimsis a waveform display representative of a biomedical phenomenon, comprising the steps of generating an electron beam;

" rafiaragai electron sensitive medium orasieaere'rrniaw width in position capable of receiving impingement of said generated electron beam for providing a waveform display in response to said impingement;

providing a periodic signal;

periodically horizontally scanning said electron beam across said width of said electron sensitive medium in response to said periodic signal;

providing an electrical signal having a voltage amplifier representative of said biomedical phenomenon;

amplifying the voltages of said provided electrical signals;

providing a direct current reference signal, the voltage level of which periodically varies in a decreasing stepped sequence,

synchronizing said direct current reference signal in acl cordance with said periodic signal to provide a consecutive scan of said electron beam across said width of said electron sensitive medium once during the duration of each said reference signal voltage level;

summing said voltages of said amplified electrical signal and said direct current reference signal to provide a summed signal representative thereof; and

vertically deflecting said electron beam in response to the of the biomedical phenomenon is an electrocardiographic signal, which method further comprises variably amplifying said deflection of said electron beam in response to said summed signal to provide a said waveform of sufficient resolution for arrhythmia analysis of said waveform.

10. The method of claim 9, further comprising varying said periodic signal to provide a said waveform of sufficient resolution for arrhythmia analysis of said waveform.

11. The method of claim 8, further comprising blanking the impingement of said electron beam during the interval in which the level of said reference signal varies.

12. The method of claim 8, further comprising generating a second electron beam;

providing a second electron sensitive medium of a predetermined width in position capable of receiving impingement of said generated second electron beam for providing a waveform display in response to said impingement; and

alternatively providing waveform displays on each provided electron sensitive medium during alternative periodic sequences of the reference signal.

13. The system of claim 8, in which the synchronizing step comprises waveform display representative of biomedical phenomena, comprising generating an electron beam; providing an electron sensitive medium of a predetermined width in position capable of receiving impingement of said generated electron beam for providing a wavefonn display in response to said impingement; providing a periodic signal; 1 periodically horizontally scanning said electron beam across said width of said electron sensitive medium in response to said periodic signal; providing a plurality of electrical signals having voltage amplitudes representative of a. plurality of biomedical phenomena;

amplifying the voltages of said provided electrical signals;

providing a plurality of bias signals having different discrete direct current voltage levels;

multiplexing said plurality of amplified electrical signals in a predetermined periodic sequence to provide a first multiplexed signal representative thereof;

multiplexing said plurality of bias signalsin said predetermined periodic sequence to provide a second multiplexed signal representative thereof;

summing said voltages of said first and second multiplexed signals to provide a summed signal representative thereof;

vertically deflecting said electron beam in response to said summed signal to provide a multiplexed electron beam scan upon said provided electron sensitive medium representative of said plurality of amplified electrical signals to simultaneously provide a plurality of waveform displays representative of said biomedical phenomena; and

selectively providing to the summing means a single said bias signal and one of said plurality of said amplified provided electrical signals corresponding to a single said biomedical phenomenon to provide a summed signal representative of the voltages thereof for vertically deflecting said electron beam to provide as a rhythm waveform a consecutive electron beam scan upon said provided electron sensitive medium representative of said selectively provided amplified electrical signal to provide a wavefonn representative of said corresponding biomedical phenomenon, which method is characterized by the improvement further comprising providing a direct current reference signal, the voltage level of which periodically varies in a decreasing stepped sequence;

synchronizing said direct current reference signal in accordance with said periodic signal to provide a consecutive scan of said electron beam across said width of said electron sensitive medium once during the duration of each said reference signal voltage level; and

summing the voltage of said selectively provided amplified electrical signal with the voltage of said direct current reference signal to provide a summed signal representative thereof for vertically deflecting said electron beam to provide a sequential plurality of consecutive electron beam scans upon said provided electron sensitive medium representative of said selectively provided amplified signal to consecutively provide a waveform display representative of said corresponding biomedical phenomenon during each periodic stepped sequence of reference signal voltage levels.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,585 ,988 Dated June 22 1971 Inventor(s) Walter F. Creigh, Arney Landy Jr. Marvin J. Schmitz It is certified that error appears in the above-identified patent: and that said Letters Patent are hereby corrected as shown below:

Column 2, line 42, change "of" to for and line 73, change "beam" to ---beams Column line 1, change "alternatively" to alternately line 8, change "sequence" to sequencer and line 62, change "provides" to provide.

Column 7, line 2, change "NPN Transistor" to Operational Amplifier Column 11, line 4, change "amplifier" to amplitude Signed and sealed this L .th day .Jf July 1972.

(SEAL) Attest:

EDWARD M. FL ILT C HER, J R. R0 BERT GOTT S CHALK Attesting Officer Commissioner of Patents FORM PO-105O (10-69) uscoMM-Dc 603754259 h ups covuuunn rnnnmn orrlc: nu 0-3564 

1. A system for providing for physiological analysis a waveform display representative of a biomedical phenomenon, comprising; means for generating an electron beam; means operatively coupled to the electron beam generating means for providing an electron sensitive medium of a predetermined width in position capable of receiving impingement of said generated electron beam for providing a waveform display in response to said impingement; means for providing a periodic signal; means connected to the periodic signal providing means and operatively coupled to the electron beam generating means for periodically horizontally scanning said electron beam across said width of said electron sensitive medium in response to said periodic signal; means for providing an electrical signal having a voltage amplitude representative of said biomedical phenomenon; means connected to the electrical signal providing means for amplifying the voltage of said provided electrical signal; means for providing a direct current reference signal, the voltage level of which periodically varies in a decreasing stepped sequence, which means for providing said direct current reference signal comprise means for synchronizing said direct current reference signal in accordance with said periodic signal to provide a consecutive scan of said electron beam across said width of said electron sensitive medium once during the duration of each said reference signal voltage level; means operatively coupled to the amplifying means and connected to the direct current reference signal providing means for summing said voltages of said amplified electrical signal with said direct current reference signal to provide a summed signal representative thereof; and means connected to the summing means and operatively coupled to the electron beam generating means for vertically deflecting said electron beam in response to said summed signal for providing a sequential plurality of consecutive electron beam scans upon said provided electron sensitive medium representative of said amplified electrical signal to consecutively provide a waveform display representative of said biomedical phenomenon during each period stepped sequence of reference signal voltage levels.
 2. The system of claim 1, in which the signal representative of the biomedical phenomenon is an electrocardiographic signal, which system further comprises means operatively coupled to the electron beam generating means for variably amplifying said deflection of said electron beam in response to said summed signal to provide a said waveform of sufficient resolution for arrhythmia analysis of said waveform.
 3. The system of claim 2, further comprising means operatively coupled to the means for providing said periodic signal for varying said periodic signal to provide a said waveform of sufficient resolution for arrhythmia analysis of said waveform.
 4. The system of claim 1, further comprising means operatively coupled to the electron beam generating means and to the means for providing said periodic signal for blanking the impingement of said electron beam during the interval in which the level of said reference signal varies.
 5. The system of claim 1, further comprising a second means for generating a second electron beam; a second means operatively coupled to the electron beam generating means for providing a second electron sensitive medium of a predeteRmined width in position capable of receiving impingement of said generated second electron beam for providing a waveform display in response to said impingement; both of which recited second means are operatively coupled to the various means of the system in the same manner as the first recited electron beam generating means and first electron beam medium providing means are so operatively coupled; and switching means operatively coupled to the means for providing said direct current reference signal and operatively coupled to both electron beam generating means for alternatively providing waveform displays on each provided electron sensitive medium during alternative periodic sequences of the reference signal.
 6. The system of claim 1, in which the synchronizing means are connected to the periodic signal providing means for periodically varying the direct current reference signal in a stepped sequence in response to said periodic signal.
 7. A system for providing for physiological analysis a waveform display representative of biomedical phenomena, comprising means for generating an electron beam; means operatively coupled to the electron beam generating means for providing an electron sensitive medium of a predetermined width in position capable of receiving impingement of said generated electron beam for providing a waveform display in response to said impingement; means for providing a periodic signal; means connected to the periodic signal providing means and operatively coupled to the electron beam generating means for periodically horizontally scanning said electron beam across said width of said electron sensitive medium in response to said periodic signal; means for providing a plurality of electrical signals having voltage amplitudes representative of a plurality of biomedical phenomena; means connected to the electrical signal providing means for amplifying the voltages of said provided electrical signals; means for providing a plurality of bias signal having different discrete direct current voltage levels; means connected to the amplifying means for multiplexing said plurality of amplified electrical signals in a predetermined periodic sequence to provide a first multiplexed signal representative thereof; means connected to the bias signal providing means for multiplexing said plurality of bias signals in said predetermined periodic sequence to provide a second multiplexed signal representative thereof; means operatively coupled to both multiplexing means for summing said voltages of said first and second multiplexed signals to provide a summed signal representative thereof; means connected to the summing means and operatively coupled to the electron beam generating means for vertically deflecting said electron beam in response to said summed signal for providing a multiplexed electron beam scan upon said provided electron sensitive medium representative of said plurality of amplified electrical signals to simultaneously provide a plurality of waveform displays representative of said biomedical phenomena; and means operatively coupled to the summing means, to the bias signal providing means and to the amplifying means for selectively providing to the summing means a single said bias signal and one of said plurality of said amplified provided electrical signals corresponding to a single said biomedical phenomenon for enabling the summing means to provide a summed signal representative of the voltages thereof to the means for vertically deflecting said electron beam to provide as a rhythm waveform a consecutive electron beam scan upon said provided electron sensitive medium representative of said selectively provided amplified electrical signal to provide a waveform representative of said corresponding biomedical phenomenon, which system is characterized by the improvement further comprising means for providing a direct current reference signal, the voltage level of which periodically varies in a decreasing stepped sequence, which means for providing said direct current reference signal comprises means for synchronizing said direct current reference signal in accordance with said periodic signal to provide a consecutive scan of said electron beam across said width of said electron sensitive medium once during the duration of each said reference signal voltage level; and means operatively coupled to the summing means, to the amplifying means and to the direct current reference signal providing means for enabling the summing means to sum the voltage of said selectively provided amplified electrical signal with the voltage of said direct current reference signal to provide a summed signal representative thereof to the means for vertically deflecting said electron beam to provide a sequential plurality of consecutive electron beam scans upon said provided electron sensitive medium representative of said selectively provided amplified signal to consecutively provide a waveform display representative of said corresponding biomedical phenomenon during each periodic stepped sequence of reference signal voltage levels.
 8. A method for providing for physiological analysis a waveform display representative of a biomedical phenomenon, comprising the steps of generating an electron beam; providing an electron sensitive medium of a predetermined width in position capable of receiving impingement of said generated electron beam for providing a waveform display in response to said impingement; providing a periodic signal; periodically horizontally scanning said electron beam across said width of said electron sensitive medium in response to said periodic signal; providing an electrical signal having a voltage amplifier representative of said biomedical phenomenon; amplifying the voltages of said provided electrical signals; providing a direct current reference signal, the voltage level of which periodically varies in a decreasing stepped sequence, synchronizing said direct current reference signal in accordance with said periodic signal to provide a consecutive scan of said electron beam across said width of said electron sensitive medium once during the duration of each said reference signal voltage level; summing said voltages of said amplified electrical signal and said direct current reference signal to provide a summed signal representative thereof; and vertically deflecting said electron beam in response to the summed signal to provide a sequential plurality of consecutive electron beam scans upon said provided electron sensitive medium representative of said amplified electrical signal to consecutively provide a waveform display representative of said biomedical phenomenon during each periodic stepped sequence of reference signal voltage levels.
 9. The method of claim 8, in which the signal representative of the biomedical phenomenon is an electrocardiographic signal, which method further comprises variably amplifying said deflection of said electron beam in response to said summed signal to provide a said waveform of sufficient resolution for arrhythmia analysis of said waveform.
 10. The method of claim 9, further comprising varying said periodic signal to provide a said waveform of sufficient resolution for arrhythmia analysis of said waveform.
 11. The method of claim 8, further comprising blanking the impingement of said electron beam during the interval in which the level of said reference signal varies.
 12. The method of claim 8, further comprising generating a second electron beam; providing a second electron sensitive medium of a predetermined width in position capable of receiving impingement of said generated second electron beam for providing a waveform display in response to said impingement; and alternatively providing waveform displays on each provided electron sensitive medium during alternative periodic sequences of the reference signal.
 13. The sysTem of claim 8, in which the synchronizing step comprises periodically varying the direct current reference signal in a stepped sequence in response to said periodic signal.
 14. A method for providing for physiological analysis a waveform display representative of biomedical phenomena, comprising generating an electron beam; providing an electron sensitive medium of a predetermined width in position capable of receiving impingement of said generated electron beam for providing a waveform display in response to said impingement; providing a periodic signal; periodically horizontally scanning said electron beam across said width of said electron sensitive medium in response to said periodic signal; providing a plurality of electrical signals having voltage amplitudes representative of a plurality of biomedical phenomena; amplifying the voltages of said provided electrical signals; providing a plurality of bias signals having different discrete direct current voltage levels; multiplexing said plurality of amplified electrical signals in a predetermined periodic sequence to provide a first multiplexed signal representative thereof; multiplexing said plurality of bias signals in said predetermined periodic sequence to provide a second multiplexed signal representative thereof; summing said voltages of said first and second multiplexed signals to provide a summed signal representative thereof; vertically deflecting said electron beam in response to said summed signal to provide a multiplexed electron beam scan upon said provided electron sensitive medium representative of said plurality of amplified electrical signals to simultaneously provide a plurality of waveform displays representative of said biomedical phenomena; and selectively providing to the summing means a single said bias signal and one of said plurality of said amplified provided electrical signals corresponding to a single said biomedical phenomenon to provide a summed signal representative of the voltages thereof for vertically deflecting said electron beam to provide as a rhythm waveform a consecutive electron beam scan upon said provided electron sensitive medium representative of said selectively provided amplified electrical signal to provide a waveform representative of said corresponding biomedical phenomenon, which method is characterized by the improvement further comprising providing a direct current reference signal, the voltage level of which periodically varies in a decreasing stepped sequence; synchronizing said direct current reference signal in accordance with said periodic signal to provide a consecutive scan of said electron beam across said width of said electron sensitive medium once during the duration of each said reference signal voltage level; and summing the voltage of said selectively provided amplified electrical signal with the voltage of said direct current reference signal to provide a summed signal representative thereof for vertically deflecting said electron beam to provide a sequential plurality of consecutive electron beam scans upon said provided electron sensitive medium representative of said selectively provided amplified signal to consecutively provide a waveform display representative of said corresponding biomedical phenomenon during each periodic stepped sequence of reference signal voltage levels. 